Reciprocating tool

ABSTRACT

An arcuate action tool attachment is adapted to receive an input and to convert that input into reciprocating output motion along an arcuate path. The tool may be adapted to be combined with an existing linear reciprocating device or a rotary device, or the tool may comprise a single unit including a linear reciprocating device or a rotary device. The tool may be fitted with one or more curved or arc-shaped accessories, such as saw blades or the like, that reciprocate along the arcuate paths that may have substantially the same radius of curvature as the accessory.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 60/897,170, filed Jan. 24, 2007, which is herebyincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to a reciprocating tool, and,more particularly, to a powered reciprocating tool that reciprocallydrives an accessory, such as a cutting blade.

BACKGROUND OF THE INVENTION

Reciprocating power tools are typically used for cutting tasks, such ascutting wood, pipe, and other materials more quickly than can normallybe accomplished by hand. Reciprocating power tools typically have a toolholder or “chuck” for mounting a straight saw blade, such that the toolholder and saw blade reciprocate linearly relative to the power tool andthe material being cut.

Frequently, such as when a work material, such as a pipe, is adjacentone or more materials that are not to be cut or damaged, such as anotherpipe or wiring, a reciprocating power tool cannot be used withoutsignificant risk of cutting or impacting the material that is not to becut or damaged. Typical reciprocating power tools are also notwell-suited for tasks such as cutting materials, such as boards, whichabut a substrate that should not be cut, such as a floor or ceiling. Insome cases, the risk may be high due to the reciprocating tool's and/oran operator's restricted access to the work material, such as when thework material is inside or adjacent a wall.

SUMMARY OF THE INVENTION

The present invention provides an arcuate action reciprocating tool thatis adapted to provide arcuate reciprocating motion of an accessory, suchas an arc-shaped saw blade, a brush, a file, or the like. The tool isoperable to move the arcuate or curved accessory back and forth along anarcuate path to enhance the operation of the tool and accessory.Further, the present invention may provide an offset blade for cuttingworkpieces adjacent a surface that is not to be cut. Methods of makingsaw blades are also provided.

In one form of the present invention, an arcuate action reciprocatingtool may have a mechanism adapted to convert substantially linearreciprocating motion into arcuate reciprocating motion along an arcuatepath. Alternatively, an arcuate action reciprocating tool of the presentinvention may have a mechanism adapted to convert rotary motion intoarcuate reciprocating motion along an arcuate path. At least oneaccessory is connected to the mechanism, the accessory being drivenalong the arcuate path.

Therefore, the arcuate action reciprocating tool allows a user to morereadily access a work material with a reciprocating accessory whilereducing the risk of damage to surrounding materials. The arcuate actionreciprocating tool may convert either linear reciprocating input motionor rotary input motion into arcuate reciprocating motion, thusincreasing the efficiency of an operation, especially efficiency of anoperation conducted on convex or round work material. The arcuate actionreciprocating tool may be adapted to receive one or more accessorieshaving similar or different functions from one another. Thus, thepresent invention allows a user to cut or perform another operation on asurface to be cut or otherwise modified, by using a curved blade orother curved accessory. This is accomplished by allowing the accessoryto reach around the work surface, presenting only a non-cuttingaccessory edge to surfaces not to be modified, and may be pulled ordrawn or moved away from the surfaces not to be modified and through ortoward the surface that is to be cut or modified.

The present invention thus produces an arc-shaped path with its sawblade or cutting, abrading, or polishing attachment, or other taskaccessory. The accessory, such as a cutting blade, a file, a brush,and/or the like, is formed with a mounting end to fit the chuck oraccessory holder, which is fitted to the accessory end of the arcuateaction tool attachment. Each accessory is shaped into an arc at itswork/contact surface, whereby the arc defined by each accessory'scontact surface is concentric about the pivot point defined by themotion of the accessory holder to which it is attached. The accessoriesmay be manufactured in a variety of arc radii to conform to the variouscurvatures of the work pieces on which the tasks are being performed. Byselecting the accessory which most closely conforms to the shape of thework piece, the user can maximize the surface area of the accessorywhich is in contact with the work piece, and thereby more efficientlyperform the task.

In another form of the present invention, a reciprocating tool has areciprocating mechanism and an accessory. The accessory has a mountingportion and a working portion. The mounting portion is substantiallyoffset from the working portion such that the accessory is reciprocallydrivable by the reciprocating mechanism and each of the mounting portionand the working portion reciprocates linearly along substantially spacedparallel paths. The working portion has an extension extending from themounting portion toward the reciprocating mechanism. Optionally, theaccessory may be U-shaped, with the accessory or blade extending fromthe tool and having at least a portion of the accessory that curves backtoward the tool and that is generally parallel to the portion of theaccessory that extends from the tool.

According to another aspect of the present invention, the reciprocatingtool further comprises an elongated support bumper coupled to thereciprocating tool. The bumper has a slot that receives the accessorynear the mounting portion and near the working portion of the accessory.Optionally, the elongated support bumper may be movably coupled to thereciprocating tool.

In yet another form of the present invention, a method of fabricating asaw blade is provided. The method includes providing a base memberhaving a first plurality of protrusions for interlocking engagement,providing a blade member having a cutting portion comprising teeth and asecond plurality of protrusions for interlocking engagement with thefirst plurality of protrusions, and interlocking the first plurality ofprotrusions with the second plurality of protrusions.

According to an aspect of the present invention, the blade member has awidth greater than a width of the base member, and the method furtherinvolves removing a quantity of material from the blade member at thesecond plurality of protrusions until the width of the blade member atthe second plurality of protrusions is approximately equal to the widthof the base member. The method also involves removing a quantity ofmaterial from alternating sides of the teeth of the blade member to forma first plurality of teeth extending beyond a plane defined by a firstside of the base member and a second plurality of teeth extending beyonda plane defined by a second side of the base member.

According to another aspect of the present invention, the method furthercomprises welding the blade member to the base member at the firstplurality of protrusions and the second plurality of protrusions afterinterlocking the first plurality of protrusions with the secondplurality of protrusions.

According to another form of the present invention, a method offabricating an arcuate saw blade having a cutting face, a non-cuttingface, and a mounting portion, is provided. The method comprisesproviding a circular saw blade having a plurality of teeth at aperimeter edge, providing a cutting die or a laser cutter, and cuttingthe non-cutting face and the mounting portion from the circular sawblade with the cutting die or the laser cutter.

According to still another form of the present invention, a method isprovided for fabricating a circular saw blade having angled cuttingsurfaces. The method involves providing a standard circular saw bladehaving cutting surfaces substantially perpendicular to a planar face ofthe standard circular saw blade, providing a cutter aligned to cut in afirst direction, providing a rotatable blade mount set at anon-perpendicular angle to the first direction, mounting the standardcircular blade to the rotatable blade mount, and cutting the cuttingsurfaces of the standard circular saw blade with the cutter to form theangled cutting surfaces. Optionally, the cutter may be a laser cutter ora grinder or a water jet cutter.

These and other objects, advantages, purposes, and features of thepresent invention will become apparent upon review of the followingspecification in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an arcuate action reciprocating tool inaccordance with the present invention, with a powered reciprocatingdevice shown in phantom;

FIG. 1B is an exploded perspective view of the arcuate actionreciprocating tool of FIG. 1A;

FIG. 1C is a sectional side elevation of the arcuate actionreciprocating tool of FIGS. 1A and 1B, shown at the beginning of a pushstroke;

FIG. 1D is a sectional side elevation of the arcuate actionreciprocating tool of FIGS. 1A-1C, shown at the beginning of a pullstroke;

FIG. 2A is a perspective view of another arcuate action reciprocatingtool in accordance with the present invention, with a portion of ahousing of the tool removed to show additional details;

FIG. 2B is an exploded perspective view of the arcuate actionreciprocating tool of FIG. 2A;

FIG. 2C is an exploded perspective view of another arcuate actionreciprocating tool in accordance with the present invention;

FIG. 3A is a top sectional view of another arcuate action reciprocatingtool in accordance with the present invention, shown at the beginning ofa push stroke;

FIG. 3B is a top sectional view of the arcuate action reciprocating toolof FIG. 3A, shown at the beginning of a pull stroke;

FIG. 4A is a top sectional view of another arcuate action reciprocatingtool in accordance with the present invention, shown at the beginning ofa pull stroke;

FIG. 4B is a top sectional view of the arcuate action reciprocating toolof FIG. 4A, shown at the beginning of a push stroke;

FIG. 4C is an exploded perspective view of the arcuate actionreciprocating tool of FIGS. 4A and 4B;

FIG. 5A is a plan view and partial sectional view of another arcuateaction reciprocating tool in accordance with the present invention,shown at the beginning of a pull stroke;

FIG. 5B is another plan view and partial sectional view of the arcuateaction reciprocating tool of FIG. 5A, shown at the beginning of a pushstroke;

FIG. 6A is a plan view and partial sectional view of another arcuateaction reciprocating tool in accordance with the present invention,shown at the beginning of a pull stroke;

FIG. 6B is another plan view and partial sectional view of the arcuateaction reciprocating tool of FIG. 5A, shown at the beginning of a pushstroke;

FIG. 7A is a side elevation view of another arcuate action reciprocatingtool in accordance with the present invention, shown connected to alinear powered reciprocating device;

FIG. 7B is an exploded perspective view of the powered arcuate actionreciprocating tool of FIG. 7A;

FIG. 8A is an exploded perspective view of an arcuate actionreciprocating tool for converting rotary motion to reciprocating motionin accordance with the present invention;

FIG. 8B is an enlarged perspective view of the area designated B in FIG.8A;

FIG. 8C is an exploded perspective view of the area designated C in FIG.8B;

FIGS. 8D-8G are sectional views taken of a cam and follower of the toolof FIGS. 8A-8C, shown in different positions;

FIG. 9A is a plan view and partial sectional view of another arcuateaction reciprocating tool for converting rotary motion to reciprocatingmotion, and shown at the beginning of a push stroke;

FIG. 9B is another plan view and partial sectional view of the arcuateaction reciprocating tool of FIG. 9A, shown at the beginning of a pullstroke;

FIGS. 10A and 10B are side elevation views of brush accessories usefulwith the arcuate action reciprocating tool of the present invention;

FIGS. 11A and 11B are views of a sanding accessory useful with thearcuate action reciprocating tool of the present invention;

FIGS. 12A and 12B are views of a wood rasp accessory useful with thearcuate action reciprocating tool of the present invention;

FIGS. 13A and 13B are views of a file accessory useful with the arcuateaction reciprocating tool of the present invention;

FIGS. 14A and 14B are views of a polisher accessory useful with thearcuate action reciprocating tool of the present invention;

FIGS. 15A-15C are side elevations of saw blade accessories useful withthe arcuate action reciprocating tool of the present invention;

FIGS. 16A-16C are side elevations of the saw blade accessories of FIGS.15A-15C, respectively, as attached to an arcuate action reciprocatingtool of the present invention;

FIG. 17A is a side elevation of a prior art reciprocating tool;

FIG. 17B is a side elevation of the prior art reciprocating tool of FIG.17A, with the blade inverted and plunge-cutting a wood member frombelow;

FIGS. 18A-D are side elevations of the prior art reciprocating tool FIG.17A, showing the process of plunge-cutting a wood member from above withthe blade inverted;

FIG. 19A is a side elevation of an offset blade in accordance with thepresent invention;

FIG. 19B is a side elevation of the offset blade of FIG. 19A incombination with a reciprocating tool, and beginning a plunge-cut of awood member from above;

FIG. 20A is a side elevation of a second offset blade in accordance withthe present invention;

FIG. 20B is a side elevation of the offset blade of FIG. 20A incombination with a reciprocating tool, and beginning a plunge-cut of awood member from above;

FIG. 21A is a side elevation of another offset blade in accordance withthe present invention;

FIG. 21B is a side elevation of the offset blade of FIG. 21A incombination with a reciprocating tool, and beginning a plunge-cut of awood member from above;

FIG. 22A is a side elevation of the offset blade of FIG. 21A incombination with a reciprocating tool of the present invention having aninverted trigger handle, a movable hilt, a forward handle, and anelongated support bumper;

FIG. 22B is a side elevation of the offset blade of FIG. 21A incombination with a reciprocating tool of the present invention having adouble-trigger handle, a hilt, a forward handle, and an elongatedsupport bumper;

FIGS. 23A-C are side elevations of offset blades in combination with thereciprocating tool of FIG. 22A, showing the process of plunge-cutting awood member from above;

FIGS. 24A-C are side elevations of the offset blade of FIG. 19A incombination with the reciprocating tool of FIG. 22A, showing the processof plunge-cutting a wood member from above;

FIGS. 25A-C are side elevations of the offset blade of FIG. 21A incombination with the reciprocating tool of FIG. 22A, showing the processof plunge-cutting a wood member from above;

FIG. 26 is a side elevation of the offset blade of FIG. 21A and thedouble-triggered reciprocating tool of FIG. 22B, having completed aplunge-out of a wood member from below;

FIG. 27 is a side elevation of the offset blade of FIG. 19A incombination with the double-triggered reciprocating tool of FIG. 22B,and having completed a plunge-cut of a wood member from below;

FIG. 28A is another offset blade made via a blade-fabrication method inaccordance with the present invention;

FIG. 28B is a side elevation of the offset blade of FIG. 28A, showing abase member and a separate blade member;

FIG. 28C is a side elevation of another offset blade made in accordancewith the blade-fabrication method of the present invention;

FIG. 28D is a side elevation of another offset blade made in accordancewith the blade-fabrication method of the present invention;

FIG. 29 is an enlarged side elevation of a portion of the fourth offsetblade of FIG. 28A designated section XXIX in FIG. 28A;

FIGS. 30A-C are end elevation views of a portion of a blade, and showingfabrication steps in accordance with the first method of bladefabrication;

FIG. 31 is a top plan view of a standard circular saw blade showing apattern for cutting three arcuate saw blades therefrom;

FIG. 32 is a top plan view of a standard circular saw blade blankshowing a pattern for cutting five arcuate saw blades therefrom;

FIG. 33 is a top plan view of a standard circular saw blade blankshowing a pattern for cutting seven arcuate saw blades therefrom;

FIG. 34A is a top plan view of a system for preparing angled cuttingedges in a circular saw blade blank;

FIG. 34B is a side elevation of the system of FIG. 34A;

FIGS. 35A-C are top plan views of an arcuate blade-cutting process thatmay be performed with the system of FIGS. 34A and 34B; and

FIGS. 36A-C are sectional side elevations of portions of the standardcircular saw blade blank of FIGS. 35A-C taken along section lines A-A,B-B, and C-C, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Overview

An arcuate action tool attachment converts a driver input, such as alinear reciprocating driver input, or a rotary or rotational driverinput, into arcuate reciprocating motion of an accessory. The arcuateaction tool attachment may be attached to a powered drive device that iselectrically or battery powered to drive an accessory or saw bladeattached thereto. For example, the powered drive device may comprise alinear reciprocating device that linearly drives or reciprocates adriver attached thereto, such as shown in the illustrated embodiment ofFIGS. 1A-1D. Such a linear reciprocating device may comprise any powertool, typically electrically powered or battery powered, that produceslinear reciprocating motion, such as a reciprocating saw or similardevice. Such a linear reciprocating device typically includes a chuck ortool holder adapted to receive a saw blade, for example.

Optionally, the arcuate action tool attachment may comprise arotationally driven reciprocating device, where the powered drive devicemay comprise a rotational drive tool that rotationally drives anaccessory or tool or drill bit attached thereto. Rotational drive devicemay be any power tool, typically electrically powered or batterypowered, that produces rotary motion, such as a power drill or the like.Rotational drive devices typically include a chuck or tool holderadapted to receive a drill bit, for example.

It is further envisioned that the powered drive device may be equippedwith two or more triggers to facilitate use of the arcuate action toolattachment in various orientations, as discussed below.

The arcuate tool attachment may be adapted to receive an accessory, andmay further be adapted to receive two different accessoriessimultaneously. The accessories may be configured to engage a workmaterial along one or more sides of the accessories. The function ofaccessories and the various embodiments of the arcuate action toolattachment and powered drive tool or device will be discussed in moredetail below.

Linear-Conversion Arcuate Action Tool Attachment

Referring now to the drawings and the illustrative embodiments depictedtherein, an arcuate reciprocating device 118 includes an arcuate actiontool attachment 120, which is configured to attach to a powered drivedevice 22 (FIG. 1A). Arcuate reciprocating device 118 is operable toreciprocate or move back and forth an accessory 32, such as a curved sawblade, along an arcuate path. Arcuate action tool attachment 120includes an arc-shaped rod 134, a housing 136, one or more guides orseals 138, a connecting link 140, an accessory holder 142, covers 144, abracket 146, and the accessory 32 (FIGS. 1B-1D). In the illustratedembodiment, powered drive device 22 comprises a linearly reciprocaldriver or drive shaft 148, and an adapter coupling 149. Arcuate actiontool attachment 120 is attachable to powered drive device 22 at adaptercoupling 149. Arc-shaped rod 134 and accessory 32 are coupled to adapterlink 150, which is coupled to adapter coupling 149, and are movablealong an arcuate path in response to actuation of powered drive device22, as discussed below.

Housing 136 of arcuate action tool attachment 120 may be made of twohalves 136 a, 136 b, with each half being substantially a mirror imageof the other. In the illustrated embodiment, each half 136 a, 136 b hasan arc-shaped groove 158 formed at an inner surface 154 a, 154 b of ablock portion or region 154 of housing 136. Grooves 158 each form halfof an arc-shaped channel 160 when inner surfaces 154 a, 154 b of a blockportion or region 154 are mated together. When the housing halves 136 a,136 b are mated together, channel 160 has substantially the same orslightly larger diameter than rod 134. Channel 160 receives rod 134 andhas substantially the same radius of curvature as rod 134 so that rod134 is movable along channel 160 in its longitudinal, arcuate pathwithout binding in the channel. Housing 136 includes a linkage aperture152 at one or both halves 136 a, 136 b that provides a cavity in which aseal or guide element 138, connecting link 140, linearly reciprocaldriver 148, adapter coupling 149, adapter link 150, and a portion of rod134 may be generally located at an inner end of channel 160. Housing 136also provides an accessory holder aperture or guide 156, which providesa cavity in which accessory holder 142, a seal or guide element 138, aportion of accessory 32, and a portion of rod 134 may be generallylocated at an outer end of channel 160. Housing 136 may be made of apolymer, a self-lubricating bearing material, or metal, for example, orother strong and substantially rigid material, while remaining withinthe spirit and scope of the present invention.

In the illustrated embodiment, arc-shaped rod 134 is shown having acircular cross section, though any cross section that may be received bychannel 160 will suffice. Likewise, in the illustrated embodiment,channel 160 is shown having a circular cross section, though any crosssection that may receive arc-shaped rod 134 will suffice. For example,arc-shaped rod 134 and channel 160 may have substantially correspondingcross sections or shapes, such as rectangular cross sections or othercross sectional shape or form, such that the rod 134 is moved and guidedalong the channel 160 during operation of the tool 120. As noted above,rod 134 has a radius of curvature substantially the same as that ofchannel 160, which facilitates movement of rod 134 in channel 160. Rod134 is adapted to pivotally receive connecting link 140 at its first end134 a, and is further adapted to receive at its second end 134 b theaccessory holder 142. Rod 134 may be made of any suitable material, suchas metal, for example, or other strong and substantially rigid material.

Seals or guide elements 138 may be incorporated at each end of blockregion 154. For example, one seal 138 may be located in each of linkageaperture 152 and accessory holder aperture 156. Seals 138 each define anaperture generally aligned with channel 160 to receive arc-shaped rod134 therethrough, with the aperture preferably having a similar orsubstantially the same diameter as rod 134. Seals 138 may guidearc-shaped rod 134 and may retain a lubricant within arc-shaped channel136 so that the rod may be lubricated as it moves along the channel.Seals 138 may be made of any suitable material, such as a metallicmaterial or a polymeric material, a resilient elastomeric material, orthe like.

Connecting link 140 is pivotally connected between inner or first end134 a of rod 134 and adapter link 150, which is received in or connectedto coupling 149 of powered drive device 22. As shown in FIG. 1D, a firstend 140 a of connecting link 140 is pivotally connected to adapter link150, and a second end 140 b of connecting link 140 is pivotallyconnected to inner or first end 134 a of arc-shaped rod 134. Connectinglink 140 may be made of any suitable material, such as metal, forexample, or other strong and substantially rigid material.

Adapter link 150 is releasably connected at a first end 150 a tocoupling 149 of linearly reciprocal driver 148, and is pivotallyconnected at a second end 150 b to first end 140 a of connecting link140. The first end 150 a of adapter link 150 may be configured to bereceived by coupling 149 as shown, for example, or may be incorporatedinto driver 148, depending on the particular application. Adapter link150 may be made of any suitable material, such as metal, for example, orother strong and substantially rigid material.

Accessory holder 142 is adapted to receive second end 134 b ofarc-shaped rod 134 and, further, to releasably receive accessory 32.Accessory holder 142 may include two portions such that accessory 32 isreceived between each portion, for example, and may incorporatefasteners, such as screws or set screws or the like (not shown) tofixedly hold accessory 32 to holder 142, such as in a manner similar tothat known in the art of linear reciprocating saws.

Accessory 32 is preferably curved and may have a radius of curvaturethat is substantially the same as the radii of curvature of channel 160and rod 134, and may be configured to provide various functions as willbe described in greater detail below. Accessory 32 may be releasablyreceived by accessory holder 142 so that two or more accessories may beused with the same arcuate action tool attachment 120. In theillustrated embodiment of FIGS. 1A-1D, accessory 32 comprises anarc-shaped saw blade. However, other accessories or tools may be mountedto the accessory holder, as discussed below. Such an arrangement allowsa user to switch from one task to another without changing power tools,instead only changing blades or other contact tool accessories, such asa metal file, a wood rasp, a sanding pad, a wire brush, a scrub brush, apolishing pad, or other contact tool, or the like, which may be curvedor formed in an arc-shape so as to follow the arcuate path described bythe motion of the accessory holder during operation of the reciprocatingtool in both extension and retraction strokes.

Covers 144 a, 144 b may be included for safety or to protect movingparts of arcuate action tool attachment 120, for example, and may begenerally shaped to mate with and at least partially encase housinghalves 136 a, 136 b, respectively. Covers 144 a, 144 b may have one ormore access holes or passageways 162 through which portions of arcuateaction tool attachment 120 may be accessed without removing covers 144a, 144 b. As can be seen in FIG. 1B, access holes 162 may be establishedalong cover or covers 144 a, 144 b to provide access to the adaptercoupling 149 of powered drive device 22 so as to allow for connectionand disconnection of link 150 at coupling 149, and/or to provide accessto the accessory holder 142 so as to allow for connection anddisconnection of an accessory 32, all while the cover is attached to thehousing 136.

Removable plugs or caps 164 may be provided to cover holes 162 whilearcuate action tool attachment 120 is in use. Plugs or caps 164 may beremovably retained in holes 162 such as with screw threads or byfriction or interference fit, for example. In the illustratedembodiment, the caps 164 include a body or cover portion 164 a and aplurality of retaining tabs or arms 164 b that cooperate and flex toprovide an interference fit between the arms 164 b and the covers 144 a,144 b when the caps 164 are pressed into the access holes 162. The coverportion 164 a provides a larger diameter portion that limits insertionof the cap 164 into the hole 162 and may enhance the appearance of thecover and provide a lip around the cap 164 at the cover 144 a, 144 b toprovide for easier removal of the caps 164 from the covers 144 a, 144 b.The caps 164 thus may be readily inserted into the holes 162irrespective of their orientation (and may be interchangeable betweensimilar sized holes) and may be readily removed from the holes 162, suchas with a thumbnail or other suitable prying element or instrument. Whenthe caps 164 are removed, a tool, such as a screwdriver or allen wrenchor the like, may be inserted into the access hole to adjust a set screwor the like at the coupling 149 and/or tool holder 142. Covers 144 a,144 b may be attached to housing halves 136 a, 136 b such as withfasteners, adhesives, or the like, and may be made of any suitablematerial, such as metallic or polymeric material, for example, or otherstrong and substantially rigid material.

In order to secure the attachment 120 to the powered drive device 22, amounting bracket 146 may be provided to removably affix arcuate actiontool attachment 120 to powered drive device 22. Bracket 146 may beconnected to powered drive device 22 such as with fasteners 166, and mayfurther be connected to housing 136 and/or covers 144 a, 144 b, such aswith additional fasteners (not shown) or adhesive or other suitableattachment means. Bracket 146 may be made of metal or fiber-reinforcedpolymer, for example, or other strong and substantially rigid material.

Accordingly, arcuate action tool attachment 120 incorporates adapterlink 150 to transfer linearly reciprocating motion from driver 148 toconnecting link 140, which is pivotally connected to arc-shaped rod 134.Arc-shaped rod 134 is guided along the arcuate path by channel 160 andseals 138 such that second end 134 b of rod 134 and accessory holder 142reciprocate along the arcuate path within accessory holder aperture 156.Rod 134 drives accessory holder 142 and accessory 32 along the arcuatepath in response to linear reciprocation of link 150 by driver 148.Seals engage or surround and substantially seal against the curved rod134 and limit or substantially preclude dirt or debris from entering thechannel 158, which may affect the movability of the shaft or rod alongthe channel. Covers 144 a, 144 b enclose the mechanism, and bracket 146connects arcuate action tool attachment 120 to powered drive device 22.

Arcuate action tool attachment 120 thus provides arcuate reciprocatingmotion of accessory 32 when adapter link 150 is linearly reciprocated bylinearly reciprocal driver 148 of powered drive device 22. Thus, driver148 causes adapter link 150 to reciprocate, adapter link 150 in turncauses connecting link 140 to reciprocate, and connecting link 140 inturn causes arc-shaped rod 134 to reciprocate along the arcuate path.Arc-shaped rod 134, in turn, causes accessory holder 142 and accessory32 to reciprocate along the arcuate path having substantially the sameradius of curvature as arc-shaped rod 134 and arc-shaped channel 136.Accessory 32 is thus fully retracted when driver 148 is at the beginningof its push stroke (FIG. 1C), and accessory 32 is fully extended whendriver 148 is at the beginning of its pull stroke (FIG. 1D). Becauseaccessory 32 (such as the arc-shaped saw blade) has substantially thesame radius of curvature as rod 134, such arcuate movement of theaccessory may provide an arcuate stroke for cutting via the arc-shapedsaw blade.

Optionally, and with reference to FIGS. 2A and 2B, an arcuate actiontool attachment 220 has an arc-shaped rod 234 movably mounted in ahousing 236 and between a plurality of guide rollers or guide elements260, with at least two of the guide elements 260 being located onopposite sides of arc-shaped rod 234. Guide elements 260 guidearc-shaped rod 234 along an arcuate path, which is the same orsubstantially the same arcuate path during extension and retractionstrokes (similar to channel 160 discussed above) and may compriserollers, bearings, bushings, or the like, and may be mounted to axles260 a, which may be mounted to opposite halves 236 a, 236 b of housing236. Each half 236 a, 236 b of housing 236 may receive opposite ends ofaxles 260 a, opposite sides of guides or seals 238, and arc-shaped rod234. Seals 238 may guide arc-shaped rod 234 and retain lubricant (notshown) within the area bounded by seals 238 and housing 236. Arcuateaction tool attachment 220 may further comprise a connecting link 240,an adapter link 250, covers 244 a, 244 b, a bracket 246, an accessoryholder 242, and an accessory 32, which may be substantially similar tothose components described above with reference to FIGS. 1A-1D.Accordingly, arcuate action tool attachment 220 may functionsubstantially similarly to tool attachment 120 described above, suchthat a detailed discussion of the attachments need not be repeatedherein. In the event that arc-shaped rod 234 becomes bent or otherwisecurved in a manner that is different from the radius of curvature of thearcuate path, it is envisioned that guide elements 260 (which may besimilar in construction to rollers used to bend rods or tubes during thefabrication of curved rods or tubes) may bend or straighten rod 234 toits original curved form during subsequent reciprocating motion of rod234 along guide elements 260, so that the curved rod and the accessoryonce again travel along the same arcuate paths during the extension andretraction strokes.

Optionally, and with reference to FIG. 2C, an arcuate action toolattachment 220′ has an arc-shaped rod 234′ movably mounted in a housing236′ and between a plurality of guide bushings or guide elements 260′,with at least two of the guide elements 260′ being located on oppositesides of arc-shaped rod 234′. Arc-shaped rod 234′ has a rectangularcross-section (or other non-circular cross section) to limit twisting ofthe rod within the channel and to enhance stability of the rod and bladeduring operation of the tool. Guide elements 260′ guide arc-shaped rod234′ along an arcuate path (similar to channel 160 discussed above) andmay comprise rollers, bearings, bushings, or the like, and may bemounted to a central member 236 a′ and/or opposite flank portions 236 b′of housing 236′. Central member 236 a′ and opposite flank portions 236b′ of housing 236′ may receive opposite ends of guide elements 260′,opposite sides of guides or seals 238′, and arc-shaped rod 234′. As canbe seen in FIG. 2C, the guide elements thus may engage and guide allfour sides of the arc-shaped rectangular rod to guide the rod and limittwisting or flexing of the rod as the rod is moved back and forth alongthe channel of the housing during operation of the tool. Seals 238′ mayguide arc-shaped rod 234′ and retain lubricant (not shown) within thearea bounded by seals 238′ and housing 236′. Arcuate action toolattachment 220′ may further comprise a connecting link 240′, an adapterlink 250′, covers 244 a′, 244 b′, removable plugs or caps 264′, abracket 246′, an accessory holder 242′, and an accessory 32, which maybe substantially similar to those components described above withreference to FIGS. 2A-2B. Accordingly, arcuate action tool attachment220′ may function substantially similarly to tool attachment 220described above, such that a detailed discussion of the attachments neednot be repeated herein. In the event that arc-shaped rod 234′ becomesbent or otherwise curved in a manner that is different from the radiusof curvature of the arcuate path, it is envisioned that guide elements260′ may bend or straighten rod 234 to its original curved form duringsubsequent reciprocating motion of rod 234′ along guide elements 260′.

Optionally, an arcuate action tool attachment 320 (FIGS. 3A and 3B) iscapable of reciprocally driving two accessories 32 along an arcuatepath. Arcuate action tool attachment 320 is primarily made up of a pivotarm 322, a first bracket 324, a second bracket 326, a rocker 328, aconnecting link 330, and a housing 336.

A first end 322 a of pivot arm 322 is pivotally mounted to first bracket324 with an accessory holder 342 mounted at a second end 322 b of pivotarm 322. Pivot arm 322 has a substantially longitudinal slot 322 cproximate second end 322 b for receiving and guiding a pin 334. Pivotarm 322 is thus pivotable about first end 322 a to move accessory holder342 and accessories 32 in an arcuate path having a radius of curvatureof approximately the length of pivot arm 322.

First bracket 324 is attached to, or projects from, housing 336. Firstbracket 324 provides a mount to which pivot arm 322 is mounted at pivotarm's 322 first end 322 a. Likewise, second bracket 326 is attached to,or projects from, housing 336, and may be positioned at a side ofhousing 336 opposite first bracket 324 and proximate longitudinal slot322 c in pivot arm 322. Second bracket 326 provides a mount to whichrocker 328 is pivotally mounted. First and second brackets 324, 326 maybe made of metal or from the same material as housing 336, for example,or other strong and substantially rigid material.

Rocker 328 is pivotally mounted to second bracket 326, at a generallycentral region of rocker 328, while a first end 328 a of rocker 328 ispivotally mounted to connecting link 330 and a second end 328 b ofrocker 328 incorporates pin 334 proximate the second end 328 b. Pin 334is movably disposed within longitudinal slot 322 c of pivot arm 322. Thefirst or inner end 330 a of connecting link 330 is pivotally connectedto a coupler 349 and linearly reciprocal driver 348 of a powered drivedevice, while the opposite or second end 330 b of link 330 is pivotallyconnected to first end 328 a of rocker 328.

Housing 336 is formed with accessory apertures 338 through whichportions of accessories 32 pass during operation of arcuate action toolattachment 320. Housing 336 may enclose pivot arm 322, first bracket324, second bracket 326, rocker 328, connecting link 330, accessoryholder 342, portions of accessories 32, and linearly reciprocal driver348. Housing 336 may provide a mount for first bracket 324 and secondbracket 326, or housing 336 may have first bracket 324 and secondbracket 326 formed integrally therein. Housing 336 may provide a meansfor attaching arcuate action tool attachment 320 to a powered drivedevice. Housing 336 may be made of a polymer or metal, for example, orother strong and substantially rigid material.

Accordingly, arcuate action tool attachment 320 provides arcuatereciprocating motion of accessory 32 when first end 330 a of connectinglink 330 is linearly reciprocated by driver 348, causing rocker 328 toreciprocally pivot about second bracket 326, thus reciprocally drivingpin 334 through an arcuate path within longitudinal slot 322 c, causingpivot arm 322 to reciprocally pivot about first bracket 324, causingaccessory holder 342 and accessory 32 to reciprocate along the arcuatepath and in a generally side to side manner.

Optionally, an arcuate action tool attachment 420 (FIGS. 4A-4C) iscapable of reciprocally driving two accessories 32 at an accessoryholder 442 along an arcuate path, such as in a similar manner asdescribed above. Arcuate action tool attachment 420 has one or morefollower elements, such as a first roller 466 and a second roller 468.Each roller 466, 468 follows a respective first stationary cam 470 orsecond stationary cam 472 formed or established at (or attached to) theinner walls of the housing 436. Rollers 466, 468 may be rotatablymounted at first and second ends 474 a, 474 b of one or more followerlinks 474, and rollers 466, 468 are preferably in reciprocating rollingor sliding contact with a pivot arm 422, which may be pivotally mountedat a first end 422 a to a bracket 424, and may have an accessory holder456 at a second end 422 b. Alternatively, the follower elements may benon-rotatable, such as bushings or other rigidly mounted members, whileremaining within the spirit and scope of the present invention.

A connecting link 430 is pivotally connected at a first end 430 a to alinearly reciprocal driver 448 of a powered drive device and at a secondend 430 b to first end 474 a of follower links 474. Follower links 474are shown as being curved to avoid interference with cams 470, 472.However, it should be understood that follower links 474 may have adifferent curvature than that shown, or no curvature at all, dependingon the shape and configuration of pivot arm 422, cams 470, 472, housing436, and rollers 466, 468. Follower links 474 are depicted in FIGS.4A-4C as a pair of spaced-apart links with pivot arm 422 movablydisposed therebetween, though it should be understood that a singlefollower link may provide substantially the same function. It should benoted that various parts, including pivot arm 422, follower link 474,and connecting link 430 may, for example, comprise two or more subpartsthat are joined together, as shown in FIG. 4C, without departing fromthe scope of the invention.

Accordingly, arcuate action tool attachment 420 provides arcuatereciprocating motion of accessories 32 when first end 430 a ofconnecting link 430 is linearly reciprocated by driver 448. When driver448 is extended (FIG. 4A), first roller 466 is urged upward by first cam470, first roller 466 thus urging pivot arm 422 and accessories 32upward. When driver 448 is retracted (FIG. 4B), second roller 468 isurged downward by second cam 472, and thus second roller 468 urges pivotarm 422 and accessories 32 downward. It should be understood thatdirectional references such as “upward” and “downward” are used withspecific reference to the orientation shown in the referenced figure.

Optionally, an arcuate action tool attachment 520 (FIGS. 5A and 5B) iscapable of reciprocally driving two accessories 32 along an arcuatepath, such as in a similar manner as discussed above. An arcuate actiontool attachment 520 has a pivot arm 522 pivotally connected to a bracket524 at an intermediate point 522 c of pivot arm 522, with pivot arm 522pivotally connected at a first end 522 a to a connecting link 530, andpivot arm 522 having one or more accessories 32 connected at a secondend 522 b. Pivot arm 522 may have an angled portion 522 d proximatefirst end 522 a. Connecting link 530 is pivotally connected at a firstend 530 a to a linearly reciprocal driver 548 and, as described above,is further pivotally connected at second end 530 b to first end 522 a ofpivot arm 522.

Accordingly, arcuate action tool attachment 520 provides arcuatereciprocating motion of accessories 32 when first end 530 a ofconnecting link 530 is linearly reciprocated by driver 548. When driver548 is extended (FIG. 5A), first end 522 a of pivot arm 522 is pushed byconnecting link 530, thus urging pivot arm 522 and accessories 32upward. When driver 548 is retracted (FIG. 5B), first end 522 a of pivotarm 522 is pulled by connecting link 530, thus urging pivot arm 522 andaccessories 32 downward.

Optionally, an arcuate action tool attachment 620 (FIGS. 6A and 6B) iscapable of reciprocally driving two accessories 32 along an arcuatepath. Arcuate action tool attachment 620 has a pivot arm 622 pivotallyconnected to a connecting link 630 at a first end 622 a of pivot arm622, pivot arm 622 having one or more accessories 32 connected at asecond end 622 b. Pivot arm 622 may have a curved portion 622 c at firstend 622 a such that pivot arm 622 reciprocally pivots about an axis ofrotation 622 d. Connecting link 630 is pivotally connected at a firstend 630 a to a linearly reciprocal driver 648 and, as described above,is further pivotally connected at second end 630 b to first end 622 a ofpivot arm 622. A plurality of bearing elements 638 such as rollers,bearings, bushings, or the like, may be connected to a housing 636 withaxes aligned perpendicular to the plane in which pivot arm 622 andaccessories 32 reciprocate, and arranged to provide bearing surfaces forcurved portion 622 c of pivot arm 622.

Accordingly, arcuate action tool attachment 620 provides arcuatereciprocating motion of accessories 32 when first end 630 a ofconnecting link 630 is linearly reciprocated by driver 648. When driver648 is extended (FIG. 6A), curved portion 622 c is pushed by connectinglink 630 to follow an arcuate path having axis of rotation 622 d, thusurging pivot arm 622 and accessories 32 upward. When driver 648 isretracted (FIG. 6B), curved portion 622 c is pulled by connecting link630 to follow the arcuate path having axis of rotation 622 d, thusurging pivot arm 622 and accessories 32 downward.

Optionally, an arcuate action tool attachment 720 (FIGS. 7A and 7B) hasat least one guide element 722 with a first end 722 a connected to apowered drive device 22′ and an arcuate slot 722 c proximate a secondend 722 b. A connecting link 730 is pivotally connected at a first end730 a to a linearly reciprocating driver 748, and pivotally connected ata second end 730 b to a follower assembly 774, which is adapted toreciprocally travel in an arcuate path defined by arcuate slot 722 c.Follower assembly 774 may be of a one-piece construction, or, such asshown in FIG. 7B, may comprise one or more pins or guide elements 776 athat extend through slots 722 c and a connecting link 732 and two ormore follower elements or spacers 776 b, whereby the guide elements 776a move back and forth along the slots. Connecting link 732 is disposedbetween guide elements 722 and is pivotally attached at a first end 732a to connecting link 730 and is releasably attached to an accessory 32at a second end 732 b (such as via one or more set screws or fastenersor pins or the like). Accordingly, arcuate slot 722 c guides guideelements 776 a of follower assembly 774 along the arcuate path as driver748 reciprocates linearly. Optionally, and as shown in FIGS. 7A and 7B,a powered drive device 22′ may incorporate two or more user inputs, suchas switches or triggers 30, to allow a user to operate powered drivedevice 22′ in any orientation, depending on the particular applicationfor which the tool is being used.

Rotary-Conversion Arcuate Action Tool Attachment

As noted above, an arcuate action tool attachment may also convert arotary input into reciprocating arcuate motion. For example, and asshown in FIGS. 8A-8G, an arcuate action tool attachment 820 includes acam 824 and follower 826, which may be used in combination with a pivotarm 822 to impart such arcuate reciprocating motion in response to arotational drive input. Arcuate action tool attachment has a pivot arm822, a bracket 828, a housing 836, a rotary drive shaft 848, andbearings 830.

Housing 836 preferably encloses the moving parts, and may includejournals 840 to engage bearings 830, a chamber 838 to receive follower826, a dust seal 834 that engages or at least partially covers oroverlaps a dust jacket or sealing element 832 at pivot arm 822, andaccessory apertures 846, and may further be enclosed by covers 844. Ascan be seen with reference to FIG. 8A, dust seal 834 and sealing element832 cooperate to substantially block or close off the opening in dustseal 834 through which pivot arm 822 extends, such that dust seal 834and sealing element 832 cooperate to limit or substantially precludeentry of dust or dirt or debris into a portion of the housing 836 duringoperation of the arcuate tool 820. It is envisioned that dust seal 834and dust jacket 832 may additionally serve as a stabilizer surface and astabilizer element, respectively, for guiding and stabilizing pivot arm822 during operation of the arcuate tool 820.

Pivot arm 822 incorporates follower 826 at a first end 822 a, anaccessory holder 842 and one or more accessories 32 at a second end 822b, and is pivotally mounted to a bracket 828 at an intermediate point822 c. Rotary drive shaft 848 is connected to powered drive device 22″at a first end 848 a, has cam 824 at a second end 848 b engagingfollower 826, and has one or more bearings 830 at an intermediate region848 c between first and second ends 848 a, 848 b. Sealing element 832may be disposed at an intermediate location along pivot arm 822, such asbetween intermediate point 822 c and second end 822 b, and at a locationwhere the sealing element 832 will be generally at dust seal 834 whenhousing 836 is assembled around pivot arm 822.

Cam 824 may have a single lobe 824 a, for example, rotating with rotarydrive shaft 848. Cam 824 may be made of metal or a self-lubricatingmaterial, for example, or other strong and substantially rigid material.Follower 826 may comprise a block and defines an oblong hole, such as anoval hole 826 a, that receives cam 824. Follower 826 may thus be adaptedto oscillate or reciprocate as cam 824 rotates, causing lobe 824 a tourge follower 826 back and forth, causing pivot arm 822 to pivot aboutbracket 828.

Accordingly, arcuate action tool attachment 820 provides arcuatereciprocating motion of accessories 32 when drive shaft 848 is rotatedby rotary drive powered drive device 22″. As seen in FIG. 8D, when driveshaft 848 has set cam lobe 824 a at the 9 o'clock position, follower 826is at the left-most extent of its range of motion within chamber 838. Atthis position, accessory 32 is at the right-most extent of its arcuatetravel. As seen in FIG. 8E, when drive shaft 848 has set cam lobe 824 aat the 12 o'clock position, follower 826 is at the center of its rangeof motion within chamber 838. At this position, accessory 32 is centeredbetween the right-most and left-most extents of its arcuate travel.Similarly, the 3 o'clock position of cam lobe 824 a corresponds to theleft-most extent of accessories' 32 travel (FIG. 8F), and the 6 o'clockposition of cam lobe 824 a corresponds to accessories 32 being centered(FIG. 8G). Thus, by rotating drive shaft 848, accessories 32 arereciprocally driven along an arcuate path and in a generallyside-to-side manner.

Optionally, an arcuate action tool attachment 920 (FIGS. 9A and 9B)converts a rotary input into reciprocating arcuate motion with a wormgear arrangement, and is capable of reciprocally driving two accessories32 along an arcuate path. A substantial portion of the mechanism ofarcuate action tool attachment 920 may be the same or similar to themechanism of arcuate action tool attachment 320, described above.Specifically, arcuate action tool attachment 920 has a pivot arm 922pivotally mounted to a first bracket 924 at a first end 922 a, havingaccessory holder 942 at a second end 922 b, and having a substantiallylongitudinal slot 922 c proximate accessory holder 942. A rocker 928 ispivotally mounted to a second bracket 926, rocker 928 being pivotallymounted at a first end 928 a to a connecting link 930 and having a pin934 proximate a second end 928 b, pin 934 being movably disposed withinslot 922 c. Connecting link 930 is pivotally connected at a first end930 a to a toothed gear 938 and at a second end 932 b to first end 928 aof rocker 928. Toothed gear 938 is engaged by a worm gear 940 of driveshaft 948, which is supported by bearings 944 at either side of wormgear 940 and is rotated by the rotary drive powered drive device 22″.Thus, worm gear 940 drives toothed gear 938, which causes connectinglink 930 to reciprocally drive rocker 928.

Accordingly, arcuate action tool attachment 920 provides arcuatereciprocating motion of accessories 32 when first end 930 a ofconnecting link 930 is generally linearly reciprocated in response torotation of toothed gear 938, causing rocker 928 to reciprocally pivot,thus reciprocally driving pin 934 through an arcuate path and pivotingpivot arm 922 having accessory 32 at second end 922 b.

Accessories

One or more accessories may be removably connected to the arcuate actiontool attachment, either directly, or to an accessory holder or receiveror the like, which is in turn connected to the arcuate action toolattachment. Though illustrated in FIGS. 1-9 as one or two saw blades,the accessories may also or otherwise include, for example, any one of:a wire brush 1132, 1132′ (FIGS. 10A and 10B), a sanding pad 1232 (FIGS.11A and 11B), a wood rasp 1332 (FIGS. 12A and 12B), a metal file 1432(FIGS. 13A and 13B), a polishing pad 1532 (FIGS. 14A and 14B), or thelike. To maximize contact area with a work material, it is preferablethat the accessories have an arcuate shape with approximately the sameradius of curvature as the arcuate path along which the accessoriesreciprocate. The accessories may have a different radius of curvaturethan that of the arcuate path defined by the arcuate action toolattachment, or may be straight (i.e. of infinite radius of curvature),with the effect of reducing the accessories' contact area with the workmaterial.

Optionally, the accessories may have a radius of curvature that isgreater or less than that of the arcuate path defined by the arcuateaction tool attachment, and may be adapted with an offset region suchthat the accessories 32 follow an arcuate path of greater or lesserradius than that of the arcuate path defined by the arcuate action toolattachment. For example, and as shown in FIGS. 15B and 16B, saw blade1632 has little or no offset, while saw blade 1632′ (FIGS. 15A and 16A)has an offset region 1632 a′ so as to have a reduced radius ofcurvature, and saw blade 1632″ (FIGS. 15C and 16C) has an offset region1632 a″ so as to have an increased radius of curvature. Greater orlesser radii arcuate paths may be used, for example, to maximize thecontact area of the accessory with the work material when the workmaterial has a radius of curvature that is greater or less than theradius of the arcuate path defined by the arcuate action toolattachment.

The accessories may be constructed for use at their convex surfaces(such as shown in FIGS. 10A, 10B, 14B, and 15A), or may be constructedfor use at their concave surfaces (such as shown in FIGS. 10B, 11A, 11B,12A, 12B, 13A, 13B, 14A, 14B, and 15A-15C), or may be constructed foruse at both their concave surfaces and convex surfaces (such as in thecase of a two-sided wire brush 1132′ (FIG. 10B), a two-sided polisher1532′ (FIGS. 14A and 14B), and a two-sided saw blade 1632′ (FIG. 15A),for example. It will be appreciated that although arcuate action toolattachment 320, 420, 520, 620, 820, 920 is shown having two saw bladesat a respective accessory holder, two different accessories, such as awood rasp 1332, and a sander 1232, or any selected single accessory, maybe used to provide different functions depending on the particularapplication of the tool.

Accordingly, the attachment produces an arc-shaped path with its sawblade, or other cutting, abrading, or polishing accessories (or othertask accessories), which are formed with a mounting end to fit the chuckor accessory holder and are shaped into arcuate form at theirwork/contact surfaces to make use of the unique arcuate path action ofthe attachment and to perform tasks for which they are appropriate. Forexample, one task for which the tool disclosed herein is suitable is tomake a clean plunge-cut in sheet materials, such as plywood, using a sawblade with teeth on its outer edge, and then to cut across the materialto where the material meets a perpendicular obstruction, such as whencutting an opening in a floor to a location flush with a wall withoutcutting into the wall surface. Another cutting task for which the toolmay be used is to make a clean plunge-cut into a plumbing cavity wallusing the outer convex saw blade edge and then reach around a wall studand, using the concave saw blade edge, cut a large pipe, such as a4-inch waste pipe or the like, without cutting into the stud or the wallpanel on the opposite side.

Another example of the disclosed tool's capabilities are demonstrated byits use for industrial maintenance work at, for example a petrochemicalplant, power plant, or other facility, such as follows: Using the tool'saccessories, a worker may use the concave scrub brush accessory, alongwith cleaning compounds, to remove caked dirt and grime from round steelcolumns and piping. Then, using the concave wire brush accessory, theworker may remove rust, paint, and scale using the concave metal cuttingblade, and may cut out damaged sections, cut replacement sections fromstock for welding, and may use the wire brush accessory to removewelding debris, and then, using the concave file accessory, file weldsor other raised imperfections. Optionally, and using the concaveflexible sanding pad accessory, the worker may sand the surface smoothfor paint, primer, and finish coats. Then, using the concave polishingpad accessory, the worker may apply rubbing compound or protectivesealant. These tasks may be accomplished with one power tool and a smallassortment of accessories with the finished result being an automotivequality finish on equipment that would then look professional and thatmay be easier to keep free of contaminants and to inspect for and limitor prevent potentially dangerous flaws in the equipment.

Further, although generally shown and described as a hand-held tool ortool attachment that may be adapted for use in construction andindustrial uses, it will be appreciated that the arcuate action tool ortool attachment may be a small or micro tool, such as for surgical orhobby applications, while remaining within the spirit and scope of thepresent invention. For example, an embodiment may be adapted to sawthrough bone while causing little or no damage to surrounding tissues.

Therefore, an arcuate action tool attachment is provided that may beadapted to connect to either a linear reciprocating powered drive deviceor a rotational powered drive device to create a complete arcuate actionpower tool. The attachment includes either a mechanism for converting alinear reciprocating drive input or a mechanism for converting arotational drive input, to an arcuate path output for at least oneaccessory. The accessory may be curved and may have substantially thesame radius of curvature as the arcuate path such that the accessory mayengage a substantial portion of a work surface during operation.

Optionally, a method may provide for manufacturing arcuate saw blades 32from a standard or conventional or known circular saw blade 1774 (FIG.31). To produce arcuate saw blades 32 from standard circular saw blades1774, a die-cutter or precision metal-cutting laser or water jet may beused to cut arcuate blades 32 from an outer portion of standard circularsaw blade 1774. This method of manufacturing arcuate blades 32 does notgenerally require the creation of new tooling, and produces blades thatare typically heavier duty and have more precisely manufactured teeththan typical linear reciprocating saw blades. Additionally, standardcircular blades having flawed portions may be used to produce one ormore arcuate blades 32 such that the flawed circular blade is not whollywasted.

Optionally, and as shown in FIGS. 32 and 33, a method may provide formanufacturing offset arcuate blades 1632′, 1632″ in addition to arcuateblades 32 from a standard or conventional or known circular saw bladeblank 1776. For example, arcuate blades 32, 1632′, 1632″ may be cut fromblank 1776 with a laser cutter or a water jet cutter, as will bedescribed in greater detail below.

Method of Fabricating a Circular or Arcuate Saw Blade Having AngledCutting Edges

Typical circular saw blades may be cut with a laser cutter that isoriented perpendicularly to a horizontal support surface. Therefore, theresulting teeth are typically cut with edges that are substantiallyperpendicular to the flat or planar sides of the blade.

Further, a device and method are provided for angle-cutting theleading/cutting edge of the teeth on an arcuate or circular saw blade.With reference to FIGS. 34A and 34B, a bevel-cut apparatus 1786 includesa drive shaft 1790 that is coupled to a chuck 1792, and equipped with afirst bevel gear 1794 that intermeshes with a second bevel gear 1796.Second bevel gear 1796 is coupled to an end of a support shaft 1798having a blade chuck 1800 at an opposite end. One or more studs 1802protrude axially from chuck 1800. A center bolt 1804 and a nut (notshown) are used to hold the circular saw blank 1776 (or, alternatively,standard circular saw blade 1774) to chuck 1800. Circular saw blank 1776may be placed on blade chuck 1800 such that registration holes 1778 onblank 1776 receive studs 1802 (FIG. 32) and a center spindle hole 1782receives center bolt 1804, with a nut securing or fastening blank 1776onto chuck 1800.

Circular saw blank 1776 thus may be mounted at bevel-cut apparatus 1786(FIGS. 34A and 34B) for cutting leading edges 1780 a of teeth 1784 at anangle that is non-perpendicular to planar faces 1788 a, 1788 b of blank1776 (FIGS. 35A, 35B, 36A, and 36B). With reference to FIGS. 35A-35C, aplurality of inner teeth 1784 of an arcuate saw blade 1632 may be cut ata region of blank 1776 that is spaced apart from a perimeter 1776 a ofthe blank 1776 to form arcuate blade 32 having inner teeth 1784. Inorder to cut teeth 1784 at alternating angles, blank 1776 may beinverted during cutting (FIGS. 35B and 36B), as will be described ingreater detail below. Trailing edges of teeth 1784 may then be cutperpendicular to planar faces 1788 a, 1788 b along with the remainingcontours of the arcuate blades to cut the arcuate blades from blank 1776(FIGS. 35C and 36C).

With reference to FIGS. 34A, 34B, 36A, and 36B, support shaft 1798 ispositioned at an angle such that a generally vertically directed laserbeam 1808 will create angled or beveled cuts in blank 1776. Chuck 1792is preferably computer-controlled to rotate drive shaft 1790, therebyrotating first bevel gear 1794 and second bevel gear 1796, and causingsupport shaft 1798, blade chuck 1800, and blank 1776 to index or rotatein a precisely-controlled fashion. Laser beam 1808 is positioned at thelow side of circular blank 1776, as in FIGS. 34B, 36A, and 36B, forcutting leading edges 1780 a of every other tooth 1784. After theleading edges 1780 a of every other tooth 1784 are cut in thatorientation, the laser beam 1808 may be relocated at a high portion ofcircular blank 1776 (or the blank 1776 may be flipped over) and everyother tooth 1784 not cut in the first cutting operation is cut in asecond operation substantially identical to the first, thereby givingthe teeth 1784 alternating bevel cuts as in FIGS. 35B, 36B, and 36C.Optionally, two laser beams may be provided to simultaneously cutalternating bevel cuts in teeth 1784. The trailing edges of the teethand the remaining outline or profile of the arcuate blade may then becut with laser 1808 aligned perpendicularly to planar faces 1788 a, 1788b, as in FIGS. 35C and 36C.

In addition to cutting inner teeth 1784, as in FIG. 33A-B, it will beappreciated that bevel cut apparatus 1786 may be used to cut outer teethalong an outer or convex edge of an arcuate saw blade manufactured fromcircular saw blade 1774 or circular blank 1776 in a similar manner asdescribed above.

Offset Accessories for Reciprocating Tool

Conventional reciprocating tools (such as shown in FIGS. 17A-B and18A-D) are limited in their ability to cut materials flush to asubstrate without damaging the substrate. Optionally, such knownreciprocating tools may be fitted with an offset accessory or blade thatis adapted to fit into the chuck of a reciprocating tool and allow auser to cut boards, pipes, or the like that are adjacent a substrate orother surface, without substantially damaging the substrate, asdiscussed below. When fitted with an offset blade, a reciprocating toolmay be used to cut a material flush to a substrate without causing auser to reorient the tool or to guess whether the blade has completedits cut through the material. Additionally, a reciprocating tool may beprovided with a handle that is inverted relative to the tool body,and/or may be equipped with a double-trigger handle, a forward handle, ahilt with guard, and an elongated support bumper or shoe or guard forsupporting the tool against a work piece while cutting with an offsetblade of the type disclosed herein, in order to enhance operation anduse of the reciprocating tool, as also discussed below.

A typical prior art reciprocating tool 1700 having a saw blade 1702attached thereto is shown in FIG. 17A. Optionally, the tool 1700 mayhave the saw blade 1702 installed inverted relative to the reciprocatingtool 1700 (as shown in FIG. 17B) for cutting in an upwards direction. Ascan be seen with reference to FIG. 17B, the approximate maximum depth ofcut achievable by the prior art reciprocating tool 1700 falls short ofcutting entirely through a cross member or stud or header 1704 withoutangling the tool 1700 while plunge-cutting the wooden cross member 1704that abuts a ceiling 1706.

With reference to FIGS. 18A-D, the reciprocating tool 1700 and the sawblade 1702 may cut a cross member or stud 1708 abutting a floor surface1710. For example, the saw blade 1702 may be aligned above a work pieceor wood cross member 1708 abutting a floor surface 1710 prior tobeginning a plunge-cut (FIG. 18A). The saw blade 1702 may cut the member1708 to an approximate maximum depth of cut achievable without anglingthe reciprocating tool 1700 when plunge-cutting the wood cross member1708, as shown in FIG. 18B. The reciprocating tool 1700 may then beangled (FIG. 18C) which is typically required to complete a plunge-cutbeyond that depth shown in FIG. 18B, such that a tip of blade 1702 is incontact with floor surface 1710. In order to complete the plunge-cut ofthe cross member 1708, the reciprocating tool 1700 typically must bedrawn back toward the operator (as shown in FIG. 18D).

An offset blade is provided that allows for plunge-cutting of upper orlower cross members via a linear reciprocating saw or tool, and that isconfigured to cut entirely through the cross member without requiringtilting of the tool and drawback of the tool. For example, an offsetblade 1712 has a mounting portion 1714 and a working or cutting portion1716 offset from mounting portion 1714 (FIG. 19A) such that mountingportion 1714 and cutting portion 1716 are capable of reciprocating alongseparate, parallel, and spaced paths (FIG. 19B). Cutting portion 1716includes an extension 1716 a that extends from mounting portion 1714toward the reciprocating tool. Offset blade 1712 is provided forfacilitating an improved method of cutting an object that is adjacent asurface without significantly damaging the adjacent surface (FIG. 19B).By inserting the mounting portion 1714 of offset blade 1712 into a chuck1718 of linear actuating reciprocating tool 1700, the wood cross member1708 may be plunge-cut completely through without angling thereciprocating tool 1700 or drawing back the reciprocating tool orsignificantly damaging floor surface 1710 (FIG. 19B). The plunge-cut canbe completed with a single down-stroke whereby a user can clearly seewhen cutting portion 1716 of offset blade 1712 is adjacent floor surface1710. To complete the plunge-cut with the reciprocating tool 1700 andoffset blade 1712, reciprocating tool 1700 is held inverted to preventportions of tool 1700 from contacting floor surface 1710. Where avertical stud 1720 is located adjacent the cut, a bumper or guard orshoe 1722 on reciprocating tool 1700 may be braced against vertical stud1720 and/or cross member 1708 to brace reciprocating tool 1700 duringthe cutting operation.

Optionally, and as shown in FIG. 20A, another offset blade 1724 may havea mounting portion 1726 and a working or cutting portion 1728, wherecutting portion 1728 is offset further from mounting portion 1726 thanis cutting portion 1716 from mounting portion 1714 on offset blade 1712.Cutting portion 1728 includes an extension 1728 a that extends frommounting portion 1726 toward the reciprocating tool. Offset blade 1724places cutting portion 1728 rearward and further offset relative toreciprocating tool 1700 (FIG. 20B), as compared to offset blade 1712,discussed above. Thus, offset blade 1724 allows for greater depth-of-cutthan offset blade 1712 and allows for greater leverage of force from theuser onto the blade because of the cutting portion's location closer tothe tool 1700.

Optionally, and with reference to FIGS. 21A and 21B, another offsetblade 1730 may have a mounting portion 1732 and a working or cuttingportion 1734 spaced from the mounting portion via a curved or arcuatearm or link 1733 such that blade 1730 is substantially U-shaped. Asubstantial portion of cutting portion 1734 is an extension 1734 a thatextends from mounting portion 1732 toward the reciprocating tool. Whenmounting portion 1732 is installed in chuck 1718 (FIG. 21B), cuttingportion 1734 is approximately centered below chuck 1718.

Optionally, and with reference to FIG. 22A, a reciprocating tool 1736may have an inverted trigger handle 1738, a forward handle 1740, a hilt1742 with a guard 1742 a, and an elongated shoe or support bumper 1744.Elongated support bumper 1744 is slidably or movably mounted toreciprocating tool 1736 via a rigid support member 1746 thatincorporates pins 1748 that are received in a transverse slot 1750 inelongated support bumper 1744, and guide pins 1745, to provideadditional support to support bumper 1744. Rigid support members 1746extend into openings in the reciprocating tool 1736 and are locked inplace with set screws or other fasteners, such as in a manner similar tothat known in the art. A cross bar 1747 is welded or otherwise attachedto the rigid support members 1746 to stabilize support members 1746 andto make them useable as a single unit. A spring 1752 is connected at afirst end to elongated support bumper 1744, and at a second end to rigidsupport member 1746 to bias support bumper 1744 downward, such as shownin FIG. 22A. Elongated support bumper 1744 further incorporates alongitudinal slot (not shown) for receiving and/or guiding offset blade1730 (or any other suitable blade) during operation of reciprocatingtool 1736. Forward handle 1740 is provided at hilt 1742 for improvedgrip and leverage by a user such as when pushing downward on tool 1736to perform a downward plunge-cut. Hilt 1742 comprises guard 1742 a thatprotects a user's hand from offset blade 1730. Hilt 1742 is rotatablymounted to reciprocating tool 1736 so that the guard 1742 a may beplaced in a desirable position.

With respect to alternative reciprocating tool 1736, it will beappreciated that trigger handle 1738 is oriented in a different manneras compared to that of standard reciprocating tool 1700, in order tofacilitate the use of first alternative reciprocating tool 1736 forplunge-cutting with an offset blade, such as those described above.Trigger handle 1738 is canted or angled forward to place it in anergonomic position for a user when cutting floor or ceiling-mountedframing plates or cross members 1704, 1708, or wall-mounted furringstrips, for example. Hilt 1742 is rotatable on reciprocating tool 1736,and reduces the likelihood of a user accidentally contacting the offsetblade 1712, 1724, 1730 when gripping the forward portion of thereciprocating tool 1736. The hilt 1742 is lockable in a plurality ofpositions as it is rotated to allow the user to optimize the orientationand location of the forward handle 1740 and protective guard 1742 a forvarious cutting situations. Forward handle 1740 is located at the frontend of reciprocating tool 1736, which allows the user to hold thereciprocating tool 1736 above the chuck 1718, rather than rearward ofthe hilt 1742. The location of forward handle 1740 facilitates the useof the user's weight or arm strength to press on the reciprocating tool1736 above the offset blade 1712, 1724, 1730 to more easily load theblade and to cut more efficiently. Forward handle 1740 also positionsthe user's forward hand away from the saw blade.

Optionally, and with reference to FIG. 22B a reciprocating tool 1754 mayhave a double trigger handle 1756 and an angled forward handle 1758(such as in a similar manner as described above with respect to tool 22of FIGS. 7A and 7B). Double trigger handle 1756 facilitates comfortableuse of reciprocating tool 1754 in an inverted position (as shown), or inan upright position as in a standard reciprocating tool. Angled forwardhandle 1758 is mounted at rigid support member 1746 such that hilt 1742is rotatable independently from handle 1758. Handle 1758 is angled awayfrom elongated support bumper 1744 to provide clearance for a user'shand from support bumper 1744.

During use of reciprocating tool 1736 and offset blade 1712 (and asshown in FIG. 23A), elongated support bumper 1744 is positioned at theproximal side or on the side of cross member 1708 toward the user, suchthat a substantial portion of cutting portion 1716 of offset blade 1712is in contact with cross member 1708. Optionally, and as shown in FIG.23B, when offset blade 1724 is used, elongated support bumper 1744 maybe positioned at the side of wood cross member 1708 away from the user,such that a substantial part of cutting portion 1728 of offset blade1724 is in contact with wood cross member 1708. In a similar manner, andas shown in FIG. 23C, when offset blade 1730 is used, elongated supportbumper 1744 may be positioned at the distal side of wood cross member1708 such that a substantial part of cutting portion 1734 of offsetblade 1730 is in contact with cross member 1708 during the cuttingprocess.

With reference to FIGS. 24A-C, the reciprocating tool 1736 with offsetblade 1712 and elongated support bumper 1744 may be positioned at across member 1708 at the beginning of a plunge-cut (FIG. 24A), movedpartially through the cross member 1708 in the midst of a plunge-cut(FIG. 24B), and passed fully through the cross member 1708 at the end ofa plunge-cut (FIG. 24C). At the onset of the cut, offset blade 1712 isin contact with a top portion of wood cross member 1708, while elongatedsupport bumper 1744 is in contact with wood cross member 1708 and floorsurface 1710, where it remains for the duration of the cut. As shown inFIG. 24B, offset blade 1712 moves downward and through a portion of woodcross member 1708 as it cuts the wood, while elongated support bumpermoves relative to reciprocating tool 1736 while remaining stationaryrelative to floor surface 1710 and wood cross member 1708, causingspring 1752 to extend or stretch. As shown in FIG. 24C, when offsetblade 1712 has cut completely through wood cross member 1708 and isadjacent floor surface 1710, elongated support bumper 1744 has remainedsubstantially stationary while reciprocating tool 1736 has moved furtherdownward relative to the cross member 1708 and bumper 1744, causingspring 1752 to stretch further.

With reference to FIGS. 25A-C the reciprocating tool 1736 with offsetblade 1730 may be positioned at cross member 1708 at the beginning of aplunge-cut (FIG. 25A), moved partially through the cross member 1708 inthe midst of a plunge-cut (FIG. 25B), and passed fully through the crossmember 1708 at the end of a plunge-cut (FIG. 25C). The process issubstantially the same as that depicted in FIGS. 24A-C except that inFIGS. 25A-C, elongated support bumper 1744 is not initially in contactwith floor surface 1710 due to the amount of offset of offset blade1730. Therefore, elongated support bumper 1744 initially moves withreciprocating tool 1736 until bumper 1744 contacts floor surface 1710,as in FIGS. 25B-C. Reciprocating tool 1754 may be equipped with offsetblade 1730 (FIG. 26) or offset blade 1712 (FIG. 27) for plunge-cuttingcross member 1704 such that the blades 1730, 1712 are adjacent ceilingsurface 1706 at the end of a given plunge-cut.

Accordingly, offset blades 1712, 1724, 1730 allow a user to performplunge-cuts while holding the reciprocating tool at a substantiallyconstant orientation while permitting the user to see the progress ofthe offset blade 1712, 1724, 1730 through cross member 1704, 1708 thatis adjacent surface 1706, 1710. The reciprocating tool preferably has amovable or adjustable bumper or support for supporting and/or bracingthe tool throughout the cutting process. It will be appreciated by thoseskilled in the art that offset blades 1712, 1724, 1730 are exemplary ofa broad range of accessories that may incorporate the offset featuredescribed hereinabove. For example, offset wire brushes or scrubbers,offset polishers, offset sanders, offset scrapers, offset files, and thelike may be used in place of offset blades without departing from thespirit and scope of the present invention.

Method of Fabricating Saw Blades

Saw blades typically have a plurality of teeth that are arrangedsemi-linearly such that adjacent teeth are alternately canted left andright along the length of the blade. Hardened metals are advantageousfor their retention of sharpness during use, but may suffer thedisadvantages of being difficult to sharpen and/or difficult to bend toform individual teeth in alternating left/right canted positions due tothe hardness of the material. In addition, bending individual teeth doesnot typically result in precisely formed teeth. Non-hardened metals aremore easily sharpened and formed than their hardened counterparts, buttypically do not retain sharpness as well as blades of hardened metal.

A method is provided for making a saw blade 1760 having a hardened metalblade or tooth portion 1762 and a base portion 1764 (FIGS. 28A, 28B, 29,and 30A-C). As best seen in FIG. 30A, tooth portion 1762 has a widthgreater than base portion 1764. Base portion 1764 has a plurality ofinterlocking protrusions 1766 for interlocking with a second pluralityof interlocking protrusions 1768 on tooth portion 1762 (FIGS. 28B and29). To produce blade 1760, the second plurality of interlockingprotrusions 1768 of tooth portion 1762 are intermeshed with the firstplurality of interlocking protrusions 1766 of base portion 1764, asshown in FIG. 30A. Next, the sides of tooth portion 1762 are ground atsecond plurality of interlocking protrusions 1768 to approximately thewidth of base portion 1764 at interlocking protrusions 1766 (FIG. 30B).In the grinding process, the tooth portion 1762 is formed so as to flareto the original width of tooth portion 1762 at teeth 1762A (FIG. 30C).The grinding process may fuse tooth portion 1762 and base portion 1764together at interlocking protrusions 1766, 1768, such that tooth portion1762 and base portion 1764 are joined to form saw blade 1760.Alternatively, tooth portion 1762 may be welded or otherwise affixed tobase portion 1764 to form saw blade 1760.

Optionally, tooth portion 1762 may be applied to a plurality ofdifferent base portions to create any number of different finished sawblades, such as an offset saw blade 1770 (FIG. 28C) that may be similarto offset blade 1724, discussed above, or an offset saw blade 1772 (FIG.28D) that may be similar to offset blade 1730, also discussed above, orany other shape of saw blade. Optionally, the width of the toothportions or strips may be substantially the same as the width of thebase portions, such that grinding of the tooth portion may not berequired. The blade-forming process thus may provide strips of teethformed of a hardened material that may be readily attached to or securedto the desired or appropriate blade shape, and thus provide enhancedmanufacturing of various blade shapes or configurations.

Changes and modifications in the specifically described embodiments maybe carried out without departing from the principals of the presentinvention, which is intended to be limited only by the scope of theappended claims, as interpreted according to the principles of patentlaw.

1. A reciprocating saw adapted to reciprocally drive at least one sawblade along an arcuate path, said saw comprising: a drive input member,said drive input member adapted to receive a drive input; an arcuateconverting mechanism comprising a longitudinally curved rod attached tosaid drive input member and movable along an arcuate path in anextension stroke and a retraction stroke responsive to reciprocatingmovement of said drive input member, and further comprising a saw bladeholder attached to said curved rod and movable therewith, said arcuateconverting mechanism converting said drive input into arcuatereciprocating movement of said saw blade holder; and at least one sawblade having an arcuate working surface, said saw blade mounted to saidsaw blade holder and reciprocally movable in an arcuate saw blade pathvia said arcuate converting mechanism, wherein both the extension strokeand the retraction stroke of said curved rod are along substantially thesame arcuate path as one another, and wherein a curvature of saidarcuate working surface of said at least one saw blade is substantiallythe same as or substantially parallel to a curvature of the arcuate pathof said curved rod, whereby said arcuate working surface of said atleast one saw blade traverses substantially the same arcuate path inboth the extension stroke and the retraction stroke, said saw blade andcurved rod both curving in the same direction, the curvature of said sawblade and said curved rod together extending over an angle of at least90 degrees.
 2. The reciprocating saw of claim 1, wherein said driveinput comprises a substantially linear reciprocating input, said arcuateconverting mechanism converting said substantially linear reciprocatinginput into arcuate reciprocating movement of said saw blade holder. 3.The reciprocating saw of claim 2, wherein said arcuate convertingmechanism comprises a housing having at least one guide element adaptedto guide said curved rod, said curved rod being connected to said driveinput member via a link pivotally mounted at a first end of said curvedrod, with said at least one saw blade being connected at a second end ofsaid curved rod, opposite said first end, wherein said curved rod isguided by said at least one guide element so as to be reciprocallydrivable by said drive input member along said arcuate path.
 4. Thereciprocating saw of claim 3, wherein said at least one guide elementcomprises at least one chosen from an arcuate channel, at least twobearings, at least two rollers, and at least two bushings.
 5. Thereciprocating saw of claim 3, wherein said curved rod comprises arectangular cross section.
 6. The reciprocating saw of claim 5, whereinsaid at least one guide element comprises an arcuate channel having arectangular cross section and configured to slidably engage at least aportion of said curved rod to guide said curved rod along said arcuatepath.
 7. The reciprocating saw of claim 1, wherein said drive inputcomprises a rotational drive input, said arcuate converting mechanismconverting said rotational drive input into arcuate reciprocatingmovement of said saw blade holder.
 8. The reciprocating saw of claim 1,wherein said drive input is actuatable via a user input at saidreciprocating tool.
 9. The reciprocating saw of claim 8, wherein saiddrive input is selectively actuatable via two or more user inputs sothat said reciprocating tool is usable in different orientations. 10.The reciprocating saw of claim 1, further comprising a housing, saidhousing at least partially enclosing said arcuate converting mechanism,wherein said housing defines at least one hole, said at least one holeconfigured to permit access to at least a portion of said arcuateconverting mechanism through said at least one hole, and wherein said atleast one hole is covered by a removable cover.
 11. The reciprocatingsaw of claim 1, wherein said at least one saw blade comprises a mountingportion coupled to said saw blade holder and a working portion extendingfrom said mounting portion, and wherein said working portion comprisessaid arcuate, working surface which has substantially the same radius ofcurvature of said arcuate saw blade path so that substantially theentirety of said working surface traverses said arcuate saw blade path.12. The reciprocating saw of claim 1, wherein said arcuate path of saidcurved rod and said arcuate saw blade path define substantiallyidentical radii of curvature.
 13. An attachment for converting a driveinput from a powered drive device into an arcuate output path, saidattachment comprising: a mounting portion for mounting said attachmentto the powered drive device; a converting mechanism comprising alongitudinally curved rod for converting said drive input from thepowered drive device to an arcuate reciprocating motion of a saw bladealong the arcuate output path, said curved rod being movable along anarcuate path in an extension stroke and a retraction stroke responsiveto reciprocating movement of said drive input; and a saw blade holderattached to said curved rod, said saw blade holder being coupled to asaw blade with an arcuate working surface, said saw blade holder beingmovable along the arcuate output path via said converting mechanism whensaid attachment is mounted to the drive device and when the drive deviceis actuated to generate said drive input, wherein both the extensionstroke and the retraction stroke of said curved rod are alongsubstantially the same arcuate path as one another, and wherein acurvature of said arcuate working surface of said at least one saw bladeis substantially the same as or substantially parallel to a curvature ofthe arcuate path of said curved rod, whereby the arcuate working surfaceof the saw blade traverses substantially the same arcuate output path inboth the extension stroke and the retraction stroke, said saw blade andcurved rod both curving in the same direction, the curvature of said sawblade and said curved rod together extending over an angle of at least90 degrees.
 14. The attachment of claim 13, wherein said drive inputcomprises a substantially linear reciprocating input, and saidattachment is configured to convert the substantially linearreciprocating input into the arcuate reciprocating motion.
 15. Theattachment of claim 14, wherein said converting mechanism comprises atleast one connecting link pivotally mounted between said saw bladeholder and a drive input member of the powered drive device, saidconverting mechanism further comprising at least one guide element forguiding said curved rod along said arcuate path.
 16. The attachment ofclaim 13, wherein said converting mechanism comprises a housing havingat least one guide element adapted to guide said curved rod, said curvedrod being connected to said drive input member via a link pivotallymounted at a first end of said curved rod, with said at least one sawblade being connected at a second end of said curved rod, opposite saidfirst end, wherein said curved rod is guided by said at least one guideelement so as to be reciprocally drivable by said drive input memberalong said arcuate path.
 17. The attachment of claim 13, wherein saiddrive input comprises a rotational drive input, and said attachment isconfigured to convert the rotational drive input into the arcuatereciprocating motion.
 18. The attachment of claim 13, wherein saidarcuate path of said curved rod and said arcuate output path definesubstantially identical radii of curvature.